Resolve some TODO comments which I decided did not need anything done

activerecord/lib/active_record/associations/alias_tracker.rb

@@ -16,7 +16,7 @@ def initialize(table_joins = [])
       def aliased_table_for(table_name, aliased_name = nil)
         table_alias = aliased_name_for(table_name, aliased_name)
 
-        if table_alias == table_name # TODO: Is this conditional necessary?
+        if table_alias == table_name
           Arel::Table.new(table_name)
         else
           Arel::Table.new(table_name).alias(table_alias)

activerecord/lib/active_record/associations/through_association.rb

@@ -9,12 +9,8 @@ module ThroughAssociation #:nodoc:
 
         # We merge in these scopes for two reasons:
         #
-        #   1. To get the scope_for_create on through reflection when building associated objects
-        #   2. To get the type conditions for any STI classes in the chain
-        #
-        # TODO: Don't actually do this. Getting the creation attributes for a non-nested through
-        #       is a special case. The rest (STI conditions) should be handled by the reflection
-        #       itself.
+        #   1. To get the default_scope conditions for any of the other reflections in the chain
+        #   2. To get the type conditions for any STI models in the chain
         def target_scope
           scope = super
           chain[1..-1].each do |reflection|
@@ -61,7 +57,8 @@ def construct_join_attributes(*records)
           end
         end
 
-        # TODO: Think about this in the context of nested associations
+        # Note: this does not capture all cases, for example it would be crazy to try to
+        # properly support stale-checking for nested associations.
         def stale_state
           if through_reflection.macro == :belongs_to
             owner[through_reflection.foreign_key].to_s

activerecord/lib/active_record/relation/query_methods.rb

@@ -260,7 +260,6 @@ def build_joins(manager, joins)
         join_list
       )
 
-      # TODO: Necessary?
       join_nodes.each do |join|
         join_dependency.alias_tracker.aliased_name_for(join.left.name.downcase)
       end